1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus for forming images on a recording medium by expanding and contracting ink chambers by means of piezoelectric elements and discharging ink from nozzles of the ink chambers.
2. Description of the Related Art
An image forming apparatus such as an inkjet printer forms images on recording paper by discharging ink onto the recording paper from a recording head, while relatively moving the recording head and the recording paper. The ink discharging device discharges ink from a nozzle formed in an ink chamber, by deforming the ink chamber by means of a piezoelectric element. However, in ink discharging devices of this kind, there is a problem of accidental drops, and the like, caused by cross-talk between adjacently positioned ink chambers. In order to resolve this problem, a technology for performing share mode driving where adjacent ink chambers are driven at staggered ink discharge timings is known (see Japanese Patent Application Publication No. 7-76084). This image forming apparatus causes the respective pillars on either side of each ink chamber to deform simultaneously, by generating a potential difference in these pillars. This deformation causes the ink chamber to expand or contract, and hence ink is discharged from the nozzle. If an ink chamber is not supposed to discharge ink, then the potential difference is set to zero at the respective electrodes of the pillars of the ink chamber, thereby preventing deformation of the ink chamber. In this way, accidental drops emitted by an ink chamber that is not supposed to discharge ink are prevented.